TUESDAY, Feb. 27, 2018 (HealthDay News) -- Cleaning and greening vacant lots in a city's poor neighborhoods can put a damper on gun violence and other types of crime, a new study has found.

Abandoned lots account for about 15 percent of land in U.S. cities, according to the researchers.

For the study, the researchers worked with the U.S. Forest Service to remove trash and debris from 541 vacant lots in Philadelphia and then plant grass on those lots. Eighteen months later, police reports revealed as much as a 29 percent drop in gun violence and a 22 percent decrease in burglaries. In addition, other problems -- vandalism, noise complaints, public drunkenness and illegal dumping -- had fallen by 30 percent, the study found.

People who lived near the restored vacant lots said they felt much safer when going outside, and more than three-fourths said they spent much more time outside relaxing and socializing, according to the study.

"Our findings showed that restoration of vacant land helps to deter crime and violence and represents a pragmatic upstream infrastructural investment strategy to address complex social issues in cities," study lead author Charles Branas said in a Columbia University news release. He's chair of epidemiology at Columbia's Mailman School of Public Health in New York City.

"Given a city like Philadelphia's prior experience with gun violence, the 29 percent reduction in crime reported in this trial could translate into hundreds of fewer shootings each year if the vacant land interventions tested here were scaled beyond just the locations of the study," Branas said.

"Our study shows that direct changes to vacant urban spaces may hold great promise in breaking the cycle of abandonment, violence and fear in our cities and do so in a cost-effective way that has broad, citywide scalability," he concluded.

The study findings were published online Feb. 26 in the Proceedings of the National Academy of Sciences.